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Old 11-19-2009, 04:58 PM   #1
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P0446 code - what have you replaced to fix?

A few weeks ago, the check engine, VSC OFF and TRAC warning lights came on. In 8-1/2 years and 184,000 miles, I've never had a CE light come on. So I swung by Advance Auto, borrowed their reader and found that P0446 was the culprit. I cleared the code and all was well until a few days ago - when all three lights came on again.

was out of town and just ignored them until today, when on the 8-hour drive home, the truck just reeked of gasoline fumes. I'm aware that the code is related to evaporative emissions stuff, but that's it. Has anyone dealt with the same issue and successfully replaced solenoids, charcoal canisters, etc?

I can't get the smell out of my nose.....


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Old 11-19-2009, 05:09 PM   #2
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Let me see here....During the 2000-2001 Switch Toyota introduced a new Evap system on the 2001 4 Runners. If you do in fact have a 2001 Model then you have what's called an Intrusive Style Evap System. If the vehicle is in fact a 2000 Model then you have a Early Style Non-Intrusive Evap System. Not trying to second guess you as I just want to be more productive in troubleshooting advice but have you confirmed the year by way of the VIN or Emissions label under the hood. LMK.
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Old 11-19-2009, 05:12 PM   #3
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2001 model that I purchased new, off the lot, in June, 2001. I can supply a VIN tomorrow once the fuel smell is gone from my nasal passages.....


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Old 11-19-2009, 05:40 PM   #4
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Had one the other day. The same code except it was on an '01 Silverado. Customer has been through the same code 3 times at another shop. Gas cap, purge valve, and vent solenoid had been replaced. I checked the parameters and noticed the FTPS (fuel tank pressure sensor) was reading -17.53 Hg/in with the fuel cap off!

Alldata will not allow me to copy and paste the diagnostic flow chart, but you will need to go through a series of tests and MUST have special tools and a scan tool with parameter data (not your cheap autozone code reader).
For your basic checks: make sure the fuel cap is tight and not stripped (keeps spinning instead of clicking), make sure you do not have any kinks or vacuum leaks on the EVAP lines. Now if this were a GM I would tell you by experience to go ahead and replace the FTPS but Toyota calls it vapor pressure sensor. I cannot tell you to replace this as I need to look at the data parameter. If the pressure is reading negative with the fuel cap off then it's the pressure sensor. If it's reading 0in/Hg or slightly higher then you'll need to keep digging.
According to the flow chart there are several possibilities: ECM, vapor pressure sensor, VSV, charcoal canister, and CCV. If you live in a state that has emissions testing then you'll need to just take it to a certified shop. In the state of SC we do not currently have emission testing and I tell my customers this will not affect engine operation or driveability, but if the CEL is on then when a serious problem occurs then they will not know it because the CEL has already been illuminated. They are left with the choice of either repairing the condition or pay the diagnostic charge and sign a waiver.
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Old 11-19-2009, 05:44 PM   #5
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Okay here's the deal then. Technically without the proper tools such as a Toyota Vetronix Tester, maybe a Vacuum pump and possibly a smoke machine your probably going to end up shot-gunning it. I can't tell you how many of these tests I've performed on these vehicles and have seen all possibilities come to light. First thing that usually is checked when a CEL comes on with an emission code is the gas cap was checked for tightness. Though this situation loves to throw out a P0440 for just a all around EVAP Control System Malfunction loose gas caps can do it to. But from what it sounds like you have already done this and the light has come back on. Don't fret it. Sometimes you think you can have one these EVAP problems fixed but sometimes it may take a month on some of the pre-05's to throw a code back up. This is because Toyota has incorporated what's referred to as a LA4 drive-cycle. This LA4 drive-cycle symbolizes a condition in which you have driven your vehicle in a manner similar to a drive-cycle experienced in Los Angeles at 4 P.M. Stop, Go, Stop, Go traffic followed by highway speeds and perhaps more rounds of stop, go, stop, go. What is is doing is giving the EVAP system time to perform a test in it's entirety and test the pressures at different stages correctly. Should you turn the car off before the test has been completed then the test is aborted and waits for another drive-cycle. This is why if a person drives on a few miles on the way to work and back home it make take a week or so for the light to come back on. But in troubleshooting your case lets keep it simple. Just wanted to give you a feel for your system. If not going to tell you it's not a Charcoal canister or emission lines connected to, or a Vapor Pressure Sensor or a Canister Closed Valve but let me ask you this. Pop your hood tomorrow after the fumes escape your nose and take a look around for the emission hose(s) in the engine bay. On one of these will be a green cap which is a test port for the system. If you see that then you know you're in the general area. Follow those lines around and make sure that they are all connected properly and not loose. Sometimes if the vehicle has just been serviced or someone has been under the hood it's common for these lines to become disconnected, sometimes intentionally to obtain clearance, sometimes unintentional. Hope this helps and let me know what you find as I'll be here. I am guessing that either a Valve is stuck open or a line is disconnected making you smell these strong fumes.

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Old 11-19-2009, 06:05 PM   #6
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Thanks for the prompt replies! Apart from a recent timing belt change (first at 171,000 miles) I do everything myself. I will sniff around tomorrow and report back.


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Old 11-20-2009, 09:14 AM   #7
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No chance yet to go over the truck, but I did swing by Advance Auto again today in order to read the codes and clear everything (only P0446). The smell is gone inside the truck.

I am guilty of overfilling the gas tank more times than I can remember - any chance this killed the charcoal canister?


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Old 11-20-2009, 10:04 AM   #8
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I am guilty of overfilling the gas tank more times than I can remember - any chance this killed the charcoal canister?
That's what I've always been told and yet I still continued to do it up until about a month ago when it finally caught up w/ me. Had my CEL come on and found out the bypass valve in the canister had failed (due to overfilling more than likely). Only fix was another canister. Dealer wanted $395 for the canister alone. What a joke.

I got on car-part.com instead and found a used canister at a junk yard about a couple hours north of me. The yard literally removed the canister out of a '02 4Runner w/ only 45K miles the day I called about it. Bought for $60 (including shipping). When it arrived, I yanked the old canister out and installed the new one. It's been working great ever since and no codes to speak of.
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Old 11-20-2009, 01:03 PM   #9
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That's what I've always been told and yet I still continued to do it up until about a month ago when it finally caught up w/ me. Had my CEL come on and found out the bypass valve in the canister had failed (due to overfilling more than likely). Only fix was another canister. Dealer wanted $395 for the canister alone. What a joke.

I got on car-part.com instead and found a used canister at a junk yard about a couple hours north of me. The yard literally removed the canister out of a '02 4Runner w/ only 45K miles the day I called about it. Bought for $60 (including shipping). When it arrived, I yanked the old canister out and installed the new one. It's been working great ever since and no codes to speak of.
Excellent info - I hope this is my issue as well. I'll drive for a few more weeks and see if the CEL pops on again. If so, I'll go the same route.

How's the ol' AndyMod holding up?


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Old 11-20-2009, 01:10 PM   #10
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This is a very, very common condtition that I've seen countless times. I've seen many models ( Camry's, Sentra's, Avalon's, etc. ) come in with an EVAP code. During testing when I would lift the car and remove an EVAP line to the canister fuel would sometimes come pouring out. Unless there's a problem with the gas station's pump itself please for your benefit do not continue to bump the handle until a nice round interval is achieved as it can flood into the EVAP system. Thanks for bringing this up as this is another nice point to raise while discussing EVAP systems.
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Old 11-20-2009, 02:41 PM   #11
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Excellent info - I hope this is my issue as well. I'll drive for a few more weeks and see if the CEL pops on again. If so, I'll go the same route.

How's the ol' AndyMod holding up?


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Good luck finding the problem

And yes, the switch is still working great!

Oh and BTW, here's another member's experience with the P0446: http://www.toyota-4runner.org/3rd-ge...-ol-p0446.html
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Old 11-21-2009, 03:55 PM   #12
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p0446 is the "Purge" code. Bad purge and it could be any number of things really. If you search, you can see my problems with it, and I lightly assisted Rock Slide with his problem P0446 code, and Rock Slide is a smart guy. It could be any number of the (3) VSVs (vacuum switching valves: 2 under the hood and one just outside the canister on top the spare tire) or even the canister. If you have overfilled your tank, I am told by the dealer that it takes not cents of extra gas but dollars. You have to keep on clicking it to get the gas to go into the canister. If you have done that your canister is probably toast.

If I had to do it over again, I would get a Toyota gas cap, and put it on if you havn't already. Other than that, I would take it to the stealer and have them diagnose it. They can smoke it (although smoking won't do anything for a bad purge code, it only assists in the P0440 and P0442 codes) , pressurize it, and with the Toyota hand held tester they can tell what is going on. I also did find a canister on car-part.com for $50 and it has worked great. It came off a truck with 50K on it, so don't spend $400 for a new one. They go fast at junk yards so be vigilant.

I was told by another Toyota expert that the valves on top of the gas tank go bad sometimes and need to be replaced if you have the leak codes: P0440 and / or P0442. I replaced mine in about 3 hours and $100 including all gaskets. But I was chasing the P0442 code and not the P0446 code.
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Old 11-21-2009, 06:33 PM   #13
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Andreas, stir fry really knows his way around the evap system. He helped me a ton in diagnosing my CEL related issue. If anyone can help you, he can.
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Old 11-21-2009, 07:24 PM   #14
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Quote:
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p0446 is the "Purge" code.
P0446 - Evaporative Emission Control System Vent Control Circuit
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Quote:
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Yeah...
Teens these days...
(granted I am 19 ...
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i don't want your pile of crap, i have my own, i just want your pieces off your pile of crap.
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Old 11-22-2009, 06:48 AM   #15
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Quote:
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P0446 - Evaporative Emission Control System Vent Control Circuit
Yep that is correct. The P0441 code is technically the "purge" code but the possible trouble areas and diagnosis is the same as the P0446 code per FSM. EVAP problems can be seen in one of two possible problems in general:

1) You have a leak (P0440 or "big leak" and P0442 or "small leak")

2) You have bad air flow within your EVAP system (P0446 and P0441).

The P0446 code hopefully for you can indicate a VSV that is not functioning correctly. The most common one that fails is the hardest to get to and is located just outside the canister. In fact, the dealer doesn't even stock the other 2 VSV's under the hood, but they should stock the VSV just outside the canister. This is because over time the charcoal canister looses charcoal bits and they get caught inside that VSV just outside the canister causing it to fail and not switch back and forth. The charcoal bits don't hardly ever end up in the 2 VSVs under the hood since it is a LONG way to go. You have to remove the canister to get to that VSV just outside the canister. There are LOTS of hoses to keep track of and don't put a hole in one of them or you will end up with a bigger problem in the end.

The P/N is: 90910-12264 and it should be around $50

But you don't know if that is for sure your problem. That part is the most common if you don't want to pay the $95 diagnostic fee that the stealer charges. Then that $95 can go to labor if you wish. You can either spend $50 guessing and possibly be wrong, or spend $95 and hopefully get the correct answer.

After all my research, I figured that it was better for me to spend $50 and have a high chance of fixing the problem in my financial situation. I don't know if the previous owner overfilled my gas tank at all so I didn't have any info to go by either.
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Old 11-22-2009, 07:02 AM   #16
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I tried to PM GA22RE and asked him a few questions about this as apparently he used to be a Toy tech. From MY experience on GM the p0446 code is either the vent solenoid valve stuck closed/open or the FTPS (fuel thank pressure sensor). But the only way I could truly diagnose this was with a scan tool. First I would open and close the vent solenoid w/ the tool. If it clicks on and off then I know to keep going w/ diag. I then open the fuel cap and command the purge/seal function to 100% while observing the FTPS parameters. If it reads anywhere in the negative then I know the FTPS is bad.

I'm just trying to figure out Toyota's EVAP terminologies and diagnosis shortcuts. I never got a reply from GA though. So what function does the VSV have? Sort of like a vent valve on GM (the valve on the back or side of the fuel tank to release fuel vapor pressures in the tank.)
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Quote:
Originally Posted by Tofer
"ohhh you are one hot 4runner, look at that flex... oh yeahhhh"
Quote:
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Yeah...
Teens these days...
(granted I am 19 ...
Quote:
Originally Posted by peow130 View Post
i don't want your pile of crap, i have my own, i just want your pieces off your pile of crap.
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Old 11-22-2009, 07:11 AM   #17
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Quote:
Originally Posted by Ironmike4x4 View Post
I tried to PM GA22RE and asked him a few questions about this as apparently he used to be a Toy tech. From MY experience on GM the p0446 code is either the vent solenoid valve stuck closed/open or the FTPS (fuel thank pressure sensor). But the only way I could truly diagnose this was with a scan tool. First I would open and close the vent solenoid w/ the tool. If it clicks on and off then I know to keep going w/ diag. I then open the fuel cap and command the purge/seal function to 100% while observing the FTPS parameters. If it reads anywhere in the negative then I know the FTPS is bad.

I'm just trying to figure out Toyota's EVAP terminologies and diagnosis shortcuts. I never got a reply from GA though. So what function does the VSV have? Sort of like a vent valve on GM (the valve on the back or side of the fuel tank to release fuel vapor pressures in the tank.)
It sounds like they are synonymous. I don't know if they use the same techniques to diagnose the same code though. But it sounds like to me that the GM is designed similarly to the Toyota. In a Toyota, it also can be the valve INSIDE the canister that is not functioning properly. That is what I meant by not knowing if the canister is bad, sorry if I didn't explain that earlier. That makes 6 total valves that make the 01-02 4Runner EVAP system in the Toyota work. 3 VSVs, 1 valve inside the canister and 2 valves on top the fuel tank. Since the canister is a sealed unit, you can't replace the valve inside the canister. You can replace the VSV just outside the canister. It took me about 2 hrs to replace the VSV without looking beforehand at any diagrams or pictures.

As far as diagnosis goes on the Toyota, the limit of my understanding is that they pressurize the EVAP system through the EVAP port in the engine bay. Then they switch the VSVs and monitor the pressure readings with the Toyota hand held tester.
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Old 11-22-2009, 12:55 PM   #18
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Okay to clarify some things here is the approach you are going to want to take on a Late-Style Intrusive System IF you had the following:

From the SET "Toyota Evaporative Emissions Systems Handbook (and some inserts for Diagnostic Help from myself):

DIAGNOSING THE LATE STYLE INTRUSIVE EVAP SYSTEM

IT IS RECOMMENDED THAT THE FIRST TIME YOU PERFORM THESE PROCEDURES, YOU DO IT ON A VEHICLE WITH NO PROBLEMS SO YOU CAN SEE WHAT IS NORMAL.


Note: If at any time during this inspection the pressure reading from the Vapor Pressure Switch fails to change, back out of that screen and go back in. You will have to start that part of the test again. There may be a momentary communication error that can be remedied this way, rather than starting unnecessary diagnosis.

TOOLS REQUIRED: Scantool, Hand Held Vacuum Pump, Vacuum "T", Pinch Pliers

1) SETUP-Go into Diagnosis, Setup, Unit Conversion and change air pressure and vapor pressure to "ABS" and "mmHG".

2) Go into Diagnosis, Enhanced OBDII, Active Test, select CAN CTRL VSV, User Data, and Select "Yes" for the VApor Pressure Sensor, now press ENTER. You should now see the Vapor Pressure Sensor reading on the scantool, and be able to turn the Canister Control VSV "ON" and "OFF".

3) The Vapor Pressure Sensor should read slightly above or below 762 mmHG.
762=Atmosphere.
IF the pressure sensor reads 762 mmHG there is probably a leak, and the system is open to atmosphere. If the pressure sensor reads above or below 762 mmHG, you know the system can hold pressure/vacuum. Now remove the gas cap. The pressure sensor should now read 762 mmHG w/ Gas Cap off. If it does not change, check the sensor for a restricted atmosphere port. (Back out of the test screen and go back in to be sure it is not an communication error w/ scantool)

4) If the sensor reads 777 mmHG, there is probably a short or open in the electrical circuit of the sensor. Check all wires to the EVAP Pressure Sensor for opens, or shorts to ground, between the ECM and the pressure sensor.

5) Put the gas cap back on and "T" in a handheld vacuum pump to the EVAP hose. This is the hose that runs from the EVAP VSV back to the canister. This is also the hose that has the green test fitting in it. ( Make sure your vacuum pump can hold a vacuum on it's own.)

6) Turn the Canister Control VSV "ON" (located on or near the air box); you should hear the VSV close. Note: The Canister Control VSV is a spring loaded open VSV. Pull 5-7" of vacuum with the pump. This should take 30-50 stokes of the vacuum pump.
-If 5-7" can be achieved in only a few strokes of the vacuum pump, check the EVAP hose and line for restrictions.
-If 5-7" of vacuum cannot be achieved, there is a large leak on the canister side of the system. Proceed with leak testing using the Miller EVAP pressure tester to find the source of the leak.
-If 5-7" of vacuum can be achieved, but gradually goes away, there is a small leak in the canister side of the system. Proceed with leak testing using the Miller EVAP system pressure tester to find the source of the leak.
Remember, creative use of the pinch-off pliers can help to narrow down the exact location of a leak. For example. if you cannot pull 5-7" of vacuum, pinch off the hose that runs from the canister to the CCV. If the leak is gone, you know it is in that hose. If the leak is still there, pinch off the hose between the canister and the vacuum pump. If the leak is now gone, you know it is in the canister itself. At this time you are only checking the purge lines, canister, and fresh air lines for leaks. You should NOT see pressure, as read by the Vapor Pressure Sensor, drop in the tank. If the pressure reading on the pressure sensor is dropping, the Bypass VSV or ORVR Valve is not sealing, allowing vacuum to get through to the tank. Thy Bypass VSV is spring-loaded closed. Remember when pressure testing with the Miller pressure tester, you are not pressurizing the fresh air lines to the canister, therefore you are not checking them for leaks. This includes the Canister Control VSV and all lines/hoses back to the canister.

7) After a couple of minutes with vacuum applied to the canister, turn the Canister Control VSV "OFF". Vacuum should drop to zero on the vacuum pump within 5-10 seconds or less. If it does not, check the fresh air lines/hoses from the Canister Control VSV back to the canister for restrictions. Also, check the Canister Control VSV operation. If no restrictions are found, there may be a faulty air inlet valve in the canister.

Note: While testing with vacuum, remember since the fuel will be warm, it will be expanding. There will be slight pressure increases on the scantool. (Slight increase means 1-2 mmHG in 10-30 seconds)

CHECKING BYPASS VSV, CANISTER AND TANK FOR OPERATION AND LEAKS

8) Go back to the active test menu and select the Tank Bypass VSV. Select your Vapor Pressure Sensor again in user data, now you can control the Bypass VSV and see the Vapor Pressure Sensor. Use pinch pliers to close the hose that goes from the Canister Control VSV to the canister. (This is the VSV that is mounted to the air filter housing.) Leave the Bypass VSV OFF. Pull 5-7" of vacuum again on the canister side of the system. Again, the vapor pressure sensor reading should not drop, this means the Bypass VSV is sealing. Note the vapor pressure sensor reading on the scantool and turn the Bypass VSV "ON". The vapor pressure sensor should immediately drop, this means the Bypass VSV is open and must be working. If pressure does not drop check that the Bypass VSV is working electrically and mechanically. (Be sure it is not a scantool communication problem as mentioned at the beginning of these procedures.)

9) With the Bypass VSV still open, continue operating the vacuum pump and watch the vapor pressure sensor readings drop. You are now pulling a vacuum on the entire EVAP system, just as the ECM does when it does it's self-check. The pressure will drop to 732-738 mmHG; this is the lowest pressure reading possible before the secondary vent activates. If vacuum cannot be achieved, or pressure rises quickly after you stop operating the vacuum pump, use the Miller tester to leak check the fuel tank side of the system for leaks. Repair any leaks found and retest.

10) The tank should hold this low pressure for several minutes. Remember, if the fuel is warm there will be a slight pressure increase as the fuel expands. If the system holds the vacuum you now know there are no leaks in the tank side, or the canister side of the system. (You are doing the exact same thing the ECM does when it checks the system for leaks.)

11) Look at the vapor pressure sensor reading while you remove the pinch-off pliers from the hose at the Canister Control VSV. (Make sure the hose does not stick shut after pliers are removed.) Atmosphere will enter through the Canister Control VSV, travel into the canister, through the Bypass VSV, on to the top of the fuel tank., through the rollover valve and into the fuel tank. If pressure does not increase to 755-758 mmHG within 10-30 seconds, check all the items mentioned above for restrictions.

12) Go back to the active test menu and select the EVAP VSV (ALONE).
Now start the engine. With the EVAP VSV OFF, there should be no vacuum applied to your vacuum gauge and no needle fluctuations. If there is, check the EVAP VSV for debris or reversed hoses. ( The engines vacuum hose always goes to the nipple furthest away from the electrical connector.) With the engine still running, turn the EVAP VSV ON. The vacuum gauge should fluctuate rapidly. If it does not, check the vacuum supply and check the EVAP VSV for electrical or mechanical failure.

*NOTES*

-The purge valve is also known as the purge vsv, or EVAP VSV on the scantool. The purge valve is spring-loaded closed when "off" electrically.
-The Canister Closed Valve is also referred to as the CCV, or Canister Control VSV on the scantool. The Canister Control VSV is spring loaded open when "off" electrically. (Only operates during testing; monitoring)
-The Bypass VSV is spring-loaded closed when "off" electrically. Remember, unless this valve is on electrically, you have two seperate systems. Tank side and Canister Side. (Only Operates during testing; monitoring)
-The Vapor pressure sensor may be directly mounted to the top of the tank or may be remotely mounted depending on the model vehicle. Also, it sees tank side pressure only unless the Bypass VSV is turned on electrically then it sees the entire system.

DESCRIPTION AND OPERATION

Pressure in Tank
As the pressure in the tank builds, it will unseat the tank valve assembly, travel through the charcoal canister, and exit through the fresh air drain.

Vacuum in Tank
As pressure drops in the tank, fresh air comes through the Canister Control VSV, through the air valve, through the canister, through the vacuum check valve, and into the tank through a rollover valve.

Secondary Vacuum Release
The secondary vacuum release is the one way check valve in the gas cap.

Refueling
While refueling, high pressure in the tank forces fumes through the rollover valve, out through the On-Board Refueling Vapor Recovery Valve, through the charcoal canister, and out the fresh air valve.

Purge Mode
While purging, when the EVAP VSV is turned on, it draws air in through the Canister Closed Valve, through the air inlet valve, charcoal canister, and EVAP VSV and into the engine so the hydrocarbons stored in the canister can be burned.

EVAP MONITORS, A BRIEF EXPLANATION

The monitor is when the ECM checks the EVAP system for proper operation and leaks. Understanding how the ECM checks the system is the key to understanding the types of failures you will see on vehicles.

In order for the monitors to run the following conditions must be met:

-Cold start with coolant temp and air intake temp within 12 degrees of each other.
-Coolant temp between 50-90 degrees.
-Vehicle must be driven in stop and go conditions (LA4 drive cycle).

STAGE 1: The ECM looks for the vapor pressure to increase from it's starting point. This means that there is enough fuel in the tank and that the system is basically sound. While the ECM is is looking at the pressure rise, it is purging to make sure the EVAP VSV is working. IF pressure rises the ECM will continue on to stage 2. (Anything better than Atmospheric pressure when vehicle has sat over-night.)

STAGE 2: The ECM will open the Bypass VSV, this connects the tank directly through to the canister. Then the ECM closes the Canister Control VSV sealing off the fresh air line. With the EVAP VSV on, the canister and tank will go into a low-pressure condition. The ECM looks at the vapor pressure sensor to see if this low pressure can be achieved, if it can, the ECM continues with stage 3.
(If utilizing the scantool and manually performing a EVAP cycle you will more than likely want to see pressure's go from around 762 to 765 then sink to around 740 mmHG.)

STAGE 3: Stage 3 is the actual leak check part of the monitor. If a vacuum could be achieved (no huge leaks) the ECM looks to see how quickly the pressure increases to determine how large the leak is. A very quick increase is a large leak, very slow leak a small leak, a very, very, slow increase is acceptable. After the leak check, the ECM continues on with stage 4.
(If utilizing the scantool and manually performing a EVAP cycle you are not going to wan to see anything above the threshold. Usually anything above .40 thousandths of an increase will produce a P0442 or a P0445.)

STAGE 4: Stage 4 is where the ECM checks the CCV operation and the fresh air lines for restrictions. It is looking for pressure in the tank to quickly increase when the CCV is turned off, (opened mechanically).

STAGE 5: Stage 5 is the final stage and is when the ECM checks the operation of the Bypass VSV. Before tank pressure reaches atmosphere, the ECM turns the Bypass VSV off, making it close. If the Bypass VSV is working properly, the pressure should stop rising so quickly now that the tank is once again isolated from the canister.

*NOTE*

Here's a little rule of to remember the next time one of these DTC's presents itself:

-During Stage 2 the following codes can be stored by the ECM: P0441 (Incorrect Purge Flow)
-During Stage 3 the following codes can be stored by the ECM: P0440 (EVAP Control System Malfunction), P0442 (Small leak detected), P0456 (Very small leak detected)
-During Stage 5 the following codes can be stored by the ECM: P0446 (EVAP Vent Control System Malfunction)
P.S. don't forget about P0455 (Gross leak detected)

Last edited by GA22RE; 11-22-2009 at 05:20 PM.
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Old 11-23-2009, 04:33 AM   #19
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Hey GA22RE, Where were you when I was diagnosing my EVAP system? I think to do what you explained you have to have a pretty expensive scan tool, if not a Toyota made one. Unfortunatly I think that most people don't have one unless you work for a dealer or something.

Also when you are diagnosing the EVAP system it is important to note that the gas tank must be between 1/4 and 3/4 full due to the ORVR on top the gas tank. If you are doing the EVAP monitor set drive cycle according to a TSB you have to be between 1/2 and 3/4 full tank.

You know something.....I asked the dealership for the LA#4 drive cycle and they all didn't know what I was talking about. Do you have specifics of that drive cycle?
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Last edited by stir_fry_boy; 11-23-2009 at 04:36 AM.
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Old 11-23-2009, 10:31 AM   #20
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Quote:
Originally Posted by stir_fry_boy View Post
Hey GA22RE, Where were you when I was diagnosing my EVAP system? I think to do what you explained you have to have a pretty expensive scan tool, if not a Toyota made one. Unfortunatly I think that most people don't have one unless you work for a dealer or something.

Also when you are diagnosing the EVAP system it is important to note that the gas tank must be between 1/4 and 3/4 full due to the ORVR on top the gas tank. If you are doing the EVAP monitor set drive cycle according to a TSB you have to be between 1/2 and 3/4 full tank.

You know something.....I asked the dealership for the LA#4 drive cycle and they all didn't know what I was talking about. Do you have specifics of that drive cycle?
As far as the scantool "yes" it's a huge help when diagnosing one of these systems. Yes they are expensive as would be a scantool to retrieve data for ABS systems, SRS sytems and BCM communication. There's no doubt that today's vehicle's are getting more and more exclusive to the manufacturer. In all reality when diagnosing one of these issues one is delving into an area where he/she could benefit from some training. That's what give's us all a job as we are paid according to a certain skill set. Even in Toyota dealers only certain technician's with the appropriate amount of training are allowed access to conduct some of these tests. This way it keeps less educated technicians from incorrectly diagnosing your vehicle. Don't get me wrong I don't like this exclusiveness any more than you do as it makes some tasks nearly impossible to perform by one's self. That's why each of my vehicle's that I personally use I want to be able to diagnose and understand how to service it otherwise I do not want it for a personal car. An exception would be with my wife's vehicle. I try to keep her in the Toyota, Honda, Nissan area and purchase the FSM's but am willing to accept that there may be situations where I will have to let the dealer look at it. But in all fairness there are occupations all around us that symbolize this ex: the doctor, the telecommunications technician, the electrician. All have access to the tools of their trade and strive to master their skill. So to answer that question with ingenuity a lot of these tests could be performed by a DIY'er but the scantool would definitely speed things up a bit. That's actually what I was trying to convey to the everyday guy. It can involve a lot of work that requires a lot of patience. However I was also trying to convey the idea that it was not rocket science and how to better understand this particular EVAP system and how a dealer's service department would address a problem with it. Mike I hope this helped you and please don't hesitate to pm me with any other questions.

Thanks for touching more on this subject with the fuel level. Although the directions above do talk about the having the appropriate fuel levels in a vehicle they do not explain this to well. 1/4 to 3/4 of fuel in the tank is indeed necessary.

As far as the LA4 drive-cycle what kind of specifics are you looking for? I can reference the sources I obtained this information from or are you looking for more on the specifics that this monitor was modeled after?

Last edited by GA22RE; 11-23-2009 at 10:35 AM.
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Old 11-23-2009, 10:31 AM
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